7 resultados para Native species

em Repositório Científico da Universidade de Évora - Portugal


Relevância:

70.00% 70.00%

Publicador:

Resumo:

The sea lamprey Petromyzon marinus (Linnaeus) is both an invasive non-native species in the Laurentian Great Lakes of North America and an imperiled species in much of its native range in North America and Europe. To compare and contrast how understanding of population ecology is useful for control programs in the Great Lakes and restoration programs in Europe, we review current understanding of the population ecology of the sea lamprey in its native and introduced range. Some attributes of sea lamprey population ecology are particularly useful for both control programs in the Great Lakes and restoration programs in the native range. First, traps within fish ladders are beneficial for removing sea lampreys in Great Lakes streams and passing sea lampreys in the native range. Second, attractants and repellants are suitable for luring sea lampreys into traps for control in the Great Lakes and guiding sea lamprey passage for conservation in the native range. Third, assessment methods used for targeting sea lamprey control in the Great Lakes are useful for targeting habitat protection in the native range. Last, assessment methods used to quantify numbers of all life stages of sea lampreys would be appropriate for measuring success of control in the Great Lakes and success of conservation in the native range.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The first report of the disease (“pine wilt disease”) associated with the pinewood nematode, goes back to 1905, when Yano reported an unusual decline of pines from Nagasaki. For a long time thereafter, the cause of he disease was sought, but without success. Because of the large number of insect species that were usually seen around and on infected trees, it had always been assumed that the causal agent would prove to be one of these. However, in 1971, Kiyohara and Tokushike found a nematode of the genus Bursaphelenchus in infected trees. The nematode found was multiplied on fungal culture, inoculated into healthy trees and then re-isolated from the resulting wilted trees. The subsequent published reports were impressive: this Bursaphelenchus species could kill fully-grown trees within a few months in the warmer areas of Japan, and could destroy complete forests of susceptible pine species within a few years. Pinus densiflora, P. thunbergii und P. luchuensis were particularly affected. In 1972, Mamiya and Kiyohara described the new species of nematode extracted from the wood of diseased pines; it was a named Bursaphelenchus lignicolus. Since 1975, the species has spread to the north of Japan, with the exception of the most northerly prefectures. In 1977, the loss of wood in the west of the country reached 80%. Probably as a result of unusually high summer temperatures and reduced rainfall in the years 1978 and 1979, the losses were more than 2 million m3 per year. From the beginning, B. lignicolus was always considered by Japanese scientists to be an exotic pest. But where did it come from? That this nematode could also cause damage in the USA became clear in 1979 when B. lignicolus was isolated in great numbers from wood of a 39 year-old pine tree (Pinus nigra) in Missouri which had suddenly died after the colour of its needles changed to a reddish-brown colour (Dropkin und Foudin, 2 1979). In 1981, B. lignicolus was synonymised by Nickle et al. with B. xylophilus which had been found for the first time in the USA as far back as 1929, and reported by Steiner and Buhrer in 1934. It had originally been named Aphelenchoides xylophilus, the wood-inhabiting Aphelenchoides but was recognised by Nickle, in 1970,to belong in the genus Bursaphelenchus. Its common name in the USA was the "pine wood nematode" (PWN. After its detection in Missouri, it became known that B. xylophilus was widespread throughout the USA and Canada. It occurred there on native species of conifers where, as a rule, it did not show the symptoms of pine wilt disease unless susceptible species were stressed eg., by high temperature. This fact was an illuminating piece of evidence that North America could be the homeland of PWN. Dwinell (1993) later reported the presence of B. xylophilus in Mexico. The main vector of the PWN in Japan was shown to be the long-horned beetle Monochamus alternatus, belonging to the family Cerambycidae. This beetle lays its eggs in dead or dying trees where the developing larvae then feed in the cambium layer. It was already known in Japan in the 19th century but in the 1930s, it was said to be present in most areas of Japan, but was generally uncommon. However, with the spread of the pine wilt disease, and the resulting increase of weakened trees that could act as breeding sites for beetles, the populations of Monochamus spp. increased significantly In North America, other Monochamus species transmit PWN, and the main vector is M. carolinensis. In Japan, there are also other, less efficient vectors in the genus Monochamus. Possibly, all Monochamus species that breed in conifers can transmit the PWN. The occasional transmission by less efficient species of Monochamus or by some of the many other beetle genera in the bark or wood is of little significance. In Europe, M. galloprovincialis and M. sutor transmits the closely related species B. mucronatus. Some speculate that these two insect species are “standing by” and waiting for the arrival of B. xylophilus. In 1982, the nematode was detected and China. It was first found in dead pines near the Zhongshan Monument of Nanjing (CHENG et. al. 1983); 265 trees were then killed by pine wilt disease. Despite great efforts at eradication in China, the nematode spread further and pine wilt disease has been 3 reported from parts of the provinces of Jiangsu, Anhui, Guangdong, Shandong, Zhejiang and Hubei (YANG, 2003). In 1986, the spread of the PWN to Taiwan was discovered and in 1989, the nematode was reported to be present in the Republic of Korea where it had first been detected in Pinus thunbergii and P. densiflora. It was though to have been introduced with packing material from Japan. PWN was advancing. In 1984, B. xylophilus was found in wood chips imported into Finland from the USA and Canada, and this was the impetus to establish phytosanitary measures to prevent any possible spread into Europe. Finland prohibited the import of coniferous wood chips from these sources, and the other Nordic countries soon followed suit. EPPO (the European and Mediterranean Plant Protection Organization) made a recommendation to its member countries in 1986 to refuse wood imports from infested countries. With its Directive of 1989 (77/93 EEC), the European Community (later called the European Union or EU) recognised the potential danger of B. xylophilus for European forests and imposed restrictions on imports into the Europe. PWN was placed on the quarantine list of the EU and also of other European countries. Later, in 1991, a dispensation was allowed by the Commission of the EU(92/13 EEC) for coniferous wood from North America provided that certain specified requirements were fulfilled that would prevent introduction.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

A distribuição da espécie D. viscosa, nativa em Portugal, foi avaliada ao longo da berma de duas estradas, do sul do país. A composição florística e a percentagem de cobertura do solo das diferentes espécies foram amostradas em áreas de berma com e sem a influência de D. viscosa, para avaliar o seu efeito nas comunidades das bermas. O efeito do corte dos arbustos foi também estudado. A espécie em estudo apresentou uma clara preferência pelas bermas, comparativamente com as áreas envolventes. Os resultados sugerem que a presença dos arbustos provoca uma diminuição na biodiversidade das bermas. As estradas estudadas devem, portanto, ser alvo de controlo da distribuição desta espécie, para impedir a sua invasão. Com base nos resultados, sugerimos que o controlo deve ser efectuado através de dois cortes, no meio da primavera para impedir a propagação de incêndios e no final do verão, para prevenir a dispersão das sementes. ABSTRACT; The distribution of the native species D. viscosa was evaluated along the road verges of two roads in southern Portugal. The plant species composition and cover were surveyed within the roadside habitats, in areas with and without D. viscosa, to evaluate its effect on road verge communities. The effect of mowing on D. viscosa shrubs was also assessed. Shrubs showed a clear preference to verges relative to the surroundings, indicating that D. viscosa seems to be invading the study road verges. Results also suggest that the presence of the shrubs decrease the plant diversity of road sides, with potential effects on animals as well. Therefore, the study roads should be considered as important targets of local and regional efforts to prevent invasions of this species. Based on our results, we suggest that to prevent D. viscosa invasion within roadside ecosystems, the control should be based on two mowings, in mid-spring to prevent fires and in late-summer to prevent seed dispersal.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

O comércio de espécies selvagens tem crescido bastante ao longo das últimas décadas. Atualmente é considerado o quarto maior tráfico ilegal no mundo, logo seguido da transação de drogas, de armas e de humanos. Estima-se que o comércio de espécies selvagens pode ultrapassar os 12 milhões de euros por ano na UE. Abrange tanto as plantas como os animais vivos; mas, nestes últimos, incluem-se também os seus derivados, tais como sejam as peles, os ossos, alimento, entre outros. O uso das espécies selvagens é bastante vastos, as espécies são utilizadas para alimentação, uso medicinal, investigação científica, comércio de peles, alimentação e o mais comum é para animais de estimação. As espécies exóticas muitas vezes tornam-se espécies exóticas invasoras, começam a ser um perigo para a biodiversidade e para as espécies nativas. O processo de invasão apresenta-se por quatro fases: dispersão ou transporte, estabelecimento, naturalização e por fim dispersão geográfica e/ou invasão. Vários são os mecanismos para combater as espécies exóticas invasoras, sendo que o mecanismo mais radical a erradicação de espécimes. Em Lisboa, estão descritas três espécies exóticas invasoras: a tartaruga da Florida Trachemys scripta, a tartaruga de Nelson Pseudemys nelsoni e a tartaruga corcunda do Mississipi Graptemys pseudogeographica; ABSTRACT: The wildlife trade is growing fast over the last decades. It is now considered the fourth largest illegal trade in the world, followed by the drugs, weapons and humans. It is estimated that trade with species can exceed 12 million € per year in the EU. This trade comprises plants or live animals; but also is derivatives, such as skins, bones, food, and others. The use of wildlife is diverse, can be for food, medical, scientific research, trade of skins, but the most common is for pets. Alien species can become invasive alien species and so they become a threat to biodiversity and for native species. The process of invasion has four phases: dispersion or transport, establishment, naturalization and geographic dispersion and/or invasion. There are several mechanisms to combat such invasive alien species: the most radical mechanism is eradication of specimens. In Lisbon, are described three invasive alien species: the red-eared slider turtle Trachemys Florida, the Florida red-bellied turtle Pseudemys nelsoni and the false map turtle Graptemys psedogeographica.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Procambarus clarkii is currently recorded from 16 European territories. On top of being a vector of crayfish plague, which is responsible for large-scale disappearance of native crayfish species, it causes severe impacts on diverse aquatic ecosystems, due to its rapid life cycle, dispersal capacities, burrowing activities and high population densities. The species has even been recently discovered in caves. This invasive crayfish is a polytrophic keystone species that can exert multiple pressures on ecosystems. Most studies deal with the decline of macrophytes and predation on several species (amphibians, molluscs, and macroinvertebrates), highlighting how this biodiversity loss leads to unbalanced food chains. At a management level, the species is considered as (a) a devastating digger of the water drainage systems in southern and central Europe, (b) an agricultural pest in Mediterranean territories, consuming, for example, young rice plants, and (c) a threat to the restoration of water bodies in north-western Europe. Indeed, among the high-risk species, P. clarkii consistently attained the highest risk rating. Its negative impacts on ecosystem services were evaluated. These may include the loss of provisioning services such as reductions in valued edible native species of regulatory and supporting services, inducing wide changes in ecological communities and increased costs to agriculture and water management. Finally, cultural services may be lost. The species fulfils the criteria of the Article 4(3) of Regulation (EU) No 1143/2014 of the European Parliament (species widely spread in Europe and impossible to eradicate in a cost-effective manner) and has been included in the “Union List”. Particularly, awareness of the ornamental trade through the internet must be reinforced within the European Community and import and trade regulations should be imposed to reduce the availability of this high-risk species.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Anglers are a recognized vector for invasive fauna, with both intentional and accidental introductions reported worldwide. * The purpose of this study was to investigate the Iberian freshwater angler's habits and perceptions related to biological invasions, using an international and bilingual survey in Spain and Portugal. * The results showed that anglers from both countries cover great distances to fish, and that they commonly visit several places and fish during consecutive days, representing a major risk for invasions. Yet, anglers' activity patterns throughout the year are not constant: the summer months involve more intense activity and, hence, entail higher risk. * In both countries, the preferred fish species were invasive, and their introductions were reported more often than native species, with motivations being country-dependent. * The use of live bait was not frequent, but sometimes invasive species were used and the release of unused bait in the water was reported very frequently. * Most anglers recognize that introductions have environmental impacts and that anglers have an active role in intentional introductions. However, only a minority is aware of the angler's role in accidental transportation of invasive species. * These findings on anglers' behaviour patterns and perceptions may be used to model invasion risks and also improve monitoring and awareness programmes led by government agencies.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

1. Anglers are a recognized vector for invasive fauna, with both intentional and accidental introductions reported worldwide. 2. The purpose of this study 2. The purpose of this study was to investigate the Iberian freshwater angler’s habits and perceptions related to biological invasions, using an international and bilingual survey in Spain and Portugal. 3. The results showed that anglers from both countries cover great distances to fish, and that they commonly visit several places and fish during consecutive days, representing a major risk for invasions. Yet, anglers’ activity patterns throughout the year are not constant: the summer months involve more intense activity and, hence, entail higher risk. 4. In both countries, the preferred fish species were invasive, and their introductions were reported more often than native species, with motivations being country-dependent. 5. The use of live bait was not frequent, but sometimes invasive species were used and the release of unused bait in the water was reported very frequently. 6. Most anglers recognize that introductions have environmental impacts and that anglers have an active role in intentional introductions. However, only a minority is aware of the angler’s role in accidental transportation of invasive species. 7. These findings on anglers’ behaviour patterns and perceptions may be used to model invasion risks and also improve monitoring and awareness programmes led by government agencies.